Projectile for a muzzle loading rifle-bore mortar

ABSTRACT

A projectile for a muzzle loading rifle-bore mortar, with the projectile having an annular, circumferential groove provided with a rifled surface; an angularly split ring is located in the groove and is of less width than the groove so that the ring can move within the groove. The ring has resiliency sufficient to permit it to expand to a diameter similar to the diameter of a rearward nonrifled area of the mortar barrel and the said nonrifled part of the barrel has a diameter similar to that of the bases of the rifling. The depth of the groove increases steadily from the rearmost to the foremost of its flank surfaces.

United States Patent 1 1 3,613,596

72 Inventor gril lvfaldeb d [56] g a gc g s l s una, we en 1 pp NO 820,567 UNITED STATES PATENTS [22] Filed AP 30 1969 34,493 2/1962 Havens 102/94 Patented o g, Wauters X [73] Assignee Forsvarets Fabriksverk 3,023,704 3/1962 Dawson et a1. 102/94 Eskustuna Sweden 3,143,074 8/1964 Jasse 102/94 Primary ExaminerRobert F. Stahl Att0rney-Eric Y. Munson ABSTRACT: A projectile for a muzzle loading rifle-bore mortar, with the projectile having an annular, circumferential [54] PROJECTILE FOR A MUZZLE LOAmNG RIFLE groove provided with a rifled surface; an angularly split ring is BORF MORTAR located in the groove and is of less width than the groove so 5 Chums 7 D'awmg that the ring can move within the groove. The ring has resilien- [52] us. Cl 102/94, y ffi to p mi it to xp to a diameter similar to the log/49,1 diameter of a rearward nonrifled area of the mortar barrel and 51 Int. Cl ..F42b 31/00, the said nonrifled P of the barrel has a diameter Similar 4% 13/22 that of the bases of the rifling. The depth of the groove in- [50] Field of Search 102/93, 94, creases i y from the rearmost t0 the foremost of its flank 49,1, 49,2 surfaces.

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PROJECTILE FOR A MUZZLE LOADING-RIFLE-BORE MORTAR This invention relates to a. projectile intended to be fired from a muzzle loading rifle-bore mortar.

It has previously been proposed to providea projectile having a resilient driving band and intended to. be fired from a muzzle loading rifled-bore mortar. In this case the projectile has a driving band that is movable in a groovehavinga width considerably greater than. the width of the driving band. The groove has a forwardly decreasing depth. Thedriving band does not interfere with the dropping of the projectile into the barrel of the mortar by gravity when loading, as the driving band is located in the rear part of the groove. At the firing of the projectile, engagement with the rifling isinsured by the driving band which is pressed forwardly by, the. pressure of the gases and increases in diameter.

The pressure of the gases in a mortarv is not constant, as the propellant charge is varied in order to obtain. different velocities. Thus, it is unsuitable to use the pressure ofthe gases to bring the driving band into engagement with the rifling.

According to the present invention the driving band is brought into engagement with the rifling without making use of the pressure of the? gases. This is accomplished by the present invention in which thegroove has a forwardly. continuously increasing depth and the driving band is obliquely split and has a resiliency suff cient to permit a radial expansion of said band to a diameter that corresponds to the diameter of a rearwardly located nonrifled part of the barrel of the mortar, which part has the same diameter as the bottoms or bases of the rifling.

Reference is to be had to the accompanying drawings in which an illustrative embodiment of the invention is .shown and in which, i

FIG. I is a view partly in section and partly in elevation of the projectile and a part of thebarrel of the mortar;

FIG. 2 is a sectional view of thedriving band and a part of the projectile, and

FIGS. 3 to 7 are sectional views of portions of the driving band, a part of the projectile and a part of the barrel of the mortar and showing the operation of the disclosed construction.

According to FIG. 1, a projectile l is shown as being located in the barrel of a rifle-bore mortar. The projectile has an annular circumferential groove 2 containing a driving band 3. The width of the groove is considerably greater than the. width of the driving band so that the band is capable of movement in the groove. The groove has a forwardly continuously increasing depth, that is, the bottom surface of the groove is the mantle surface of a truncated cone. The bottom surface ofthe groove 2 has rifles 4 extending parallel to the generatrix of the mantle surface. The depth of the rifles 4 is directly proportional to the diameter of the groove with zero-depth at the smallest diameter of the groove as will be noted in FIGS. 2 and 3.

The driving band 3 is obliquely or angularly split as shown at 7 in FIG. 1 and has a resiliency sufficient to permit radial-expansion of the band to cause it to assume a diameter corresponding to the diameter of a rearwardly located nonrifled part of the barrel, which nonrifled part has substantially the same diameter as the bottoms of the rifling.

The cross-sectional shape of the driving band 3 is illustrated in FIG. 2. The cross-sectional shape is in the form of a parallel trapezoid having a beveled outer surface 8 and a rounded surface at 9. The parallel sides or ends of the trapezoid are the two flank surfaces 10 and 11. The surface 12 which is that which is brought into engagement with the rifling of the barrel is perpendicular to the two flank surfaces. Between the outer surface 12 of the band and the rear flank surface 11 is the beveled surface 8. The remaining inner surface 13 is disposed parallel to the bottom of the rifles in the groove. The driving band is preferably made of copper or of some other suitable material.

The details of the barrel are illustrated in FIGS. 1 and 3. The muzzle 14 of the barrel is conical as shown in FIG. 3. The

greatest diameter of the same is. slightly greater than ithe diameter at the bottoms of the rifling."'lhe smallest diameter is the same as the diameter of the barrel' The barrel'has rifles [5 made in the conventional manner with right-hand or left hand twist. The area rearwardly of the rifles 15 is the loading room or chamber 16, which is nonrifled and has the same diameter as the bottoms of the rifling. The transitio n -'l 7"(FIG. l and75) between the rifles and the loading room is conical'i'.e.,"the

lower ends of the rifles 15 are beveled. The pro ectile is provided with a holder 18 for the propellant charge.

The operation of the device according to-the invention will be described with reference to FlG SL'3 to 7.

The projectile is inserted in themuzzle of =the barrel in FIG. 3. When the beveled surface 8of the driving band 3 contacts the conical muzzle l4,the resilient-driving bandis-com pressed and isthus given the same diameterJas the internal diameter of the barrel. The projectile will then slidedown into the barrel by gravity'exerted by its weight (FIG. 4): The air in the barrel between the projectileand the bottom of thebarrel is evacuated through the rifling'lsof the barrel.

When the projectile reaches the end of its-travel or the point shown in FIG. 5,'the holder for the propellant charge willcontact the firing pin at the bottom of the barrel. The resilient driving band will expand to a diameter corresponding to; the diameter of the rearwardly nonrifled part ofthe barrel part has the same diameter as the bottoms voftherillin'gl-(At the same time, the driving band will slide rearwardly in the groove 2 owing to the inertia of'the driving band, whenth'e downward movement of the projectile is abruptly stopped. V

The principle of operation at firingis illustrated in FIGS. 6 and 7. When the projectile begins to advance' in the barrel under the propelling action of the gases,the driving band will be located between the transition 17 (between the rifles -15 of the barrel andthe loading room 16) and the'rifles 4'on the bottom surface of the groove. When-the projectilemoves further forwardly the driving band will be brought-into engagement with the rifles 15 of the barrel and the driving band will bc moved rearwardly in the groove to .a'position, in-which the rear flank surface '1 l of the driving band will contact the rear flank surface 6 of the groove. When the projectile advances in the barrel, the projectile is then caused to rotate by the twisted rifles of the barrel.

lclaim: l. A projectile for a muzzle loading mortar with a bore ha v- .ing a forward rifled portion and a rearward chamber comprising, in combination a rigid body; said rigid body having a circumferential :groove formed therein and comprising a front .end, a rear end in fixed spaced-relation to said'frontend; and generally conical surface means between saidends and tapering inwardly in a direction to'ward afront' portion of the body; deformable drive band means in said groove and extending around said conical surface means,' said driveband means having a width substantially less than the width of said groove as measured between said front and rear ends, said drive band means being movable along said conical surface means to a first position adjacent said front end and in which said band is contracted and has a diameter. smaller than the diameter of the rifled portion of said bore, and to a second position in seating engagement with said rear end and in which said band is expanded by said conical surface means to a diameter greater than the rifled portion of the bore; said band being movable to said second position in response to inertia of the projectile when it is fired; whereby, said projectile can be dropped through saidrifle portion of the bore and into said chamber with said band in said first position; and said band expands to engage said rifled portion, when the projectile is fired, upon movement to said second position.

3 4 2. A projectile according to claim 1 wherein said drive band gitudinal axis of the projectile; and means comprlses said conical surface means is the exterior surface of the a ring of resilient material transversely split at an angle to rifling in the groova the longltudmal axls oflhe 5. A projectile according to claim 4 wherein the depth of A molecule a-ccordmg to elm-m 2 wherein said nng has a 5 the rifling in said groove decreases in a direction toward the uniform cross-sectional configuration. from end of Said move 4. A projectile according to claim 2 wherein the bottom of g the groove has rifling extending in a direction along the lon- 

1. A projectile for a muzzle loading mortar with a bore having a forward rifled portion and a rearward chamber comprising, in combination a rigid body; said rigid body having a circumferential groove formed therein and comprising a front end, a rear end in fixed spaced relation to said front end, and generally conical surface means between said ends and tapering inwardly in a direction toward a front portion of the body; deformable drive band means in said groove and extending around said conical surface means, said drive band means having a width substantially less than the width of said groove as measured between said front and rear ends, said drive band means being movable along said conical surface means to a first position adjacent said front end and in which said band is contracted and has a diameter smaller than the diameter of the rifled portion of said bore, and to a second position in seating engagement with said rear end and in which said band is expanded by said conical surface means to a diameter greater than the rifled portion of the bore; said band being movable to said second position in response to inertia of the projectile when it is fired; whereby, said projectile can be dropped through said rifled portion of the bore and into said chamber with said band in said first position; and said band expands to engage said rifled portion, when the projectile is fired, upon movement to said second position.
 2. A projectile according to claim 1 wherein said drive band means comprises a ring of resilient material transversely split at an angle to the longitudinal axis of the projectile.
 3. A projectile according to claim 2 wherein said ring has a uniform cross-sectional configuration.
 4. A projectile according to claim 2 wherein the bottom of the groove has rifling extending in a direction along the longitudinal axis of the projectile; and said conical surface means is the exterior surface of the rifling in the groove.
 5. A projectile according to claim 4 wherein the depth of the rifling in said groove decreases in a direction toward the front end of said groove. 